Researchers from the Shenyang Institute of Automation of the Chinese Academy of Sciences have developed a multi-mode swimming soft robotic fish. Drawing inspiration from the highly sensitive lateral line sensing system and advanced muscle actuation mechanisms of natural fish, the new design integrates actuation, perception, and control capabilities, offering significant advancements in underwater robotics.

The study, published on January 21 in IEEE Transactions on Robotics, presents a soft robotic fish that can perform four distinct swimming modes, surpassing similar systems in both versatility and sensing capabilities.

Bionic mechanisms of the soft robotic fish (Image by the research group)

The research marks significant progress in three critical areas: cooperative control strategies for multi-actuation units, the implementation of flexible embedded sensing systems, and intelligent environment-adaptive mode switching. By mimicking the mackerel's biological structure, the researchers utilized 3D printing technology to design a flexible bionic structure paired with a soft actuator. The actuator integrates three specialized components arranged in functional layers: compression springs, dielectric elastomer membranes, and flexible electrodes.

To replicate the fish's lateral line system, which detects movement and environmental changes, the researchers developed high-precision flexible strain transducers. These sensors enable the robotic fish to sense its swimming state and changes in the surrounding fluid environment, allowing it to adaptively switch to the optimal swimming modes.

Furthermore, by synergistically controlling the excitation amplitude and sequence of multiple bionic muscle units, the robotic fish successfully reproduces the various swimming modes seen in natural fish and adapts to different swimming environments.

The study were supported by the National Key R&D Program of China, the National Natural Science Foundation of China, the CAS Project for Young Scientists in Basic Research, etc.

Swimming characteristics of the robotic fish in different environments (Image by the research group)